From: Elliot Gorokhovsky <embg@fb.com>
Date: Thu, 19 Jan 2023 21:18:01 +0000 (-0800)
Subject: Fuzz the external matchfinder API
X-Git-Tag: v1.5.4^2~47^2~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=3f9f568aa6401c1902138012760d4c53780f7bb4;p=thirdparty%2Fzstd.git

Fuzz the external matchfinder API
---

diff --git a/tests/fuzz/Makefile b/tests/fuzz/Makefile
index 35a19dd89..4b5102ef1 100644
--- a/tests/fuzz/Makefile
+++ b/tests/fuzz/Makefile
@@ -34,9 +34,14 @@ ZSTDDIR = ../../lib
 PRGDIR = ../../programs
 CONTRIBDIR = ../../contrib
 
+# TODO(embg) make it possible to plug in an arbitrary matchfinder as a .o file
+MATCHFINDER_DIR = $(CONTRIBDIR)/externalMatchfinder
+MATCHFINDER_SRC = $(MATCHFINDER_DIR)/matchfinder.c
+
 FUZZ_CPPFLAGS := -I$(ZSTDDIR) -I$(ZSTDDIR)/common -I$(ZSTDDIR)/compress \
 	-I$(ZSTDDIR)/dictBuilder -I$(ZSTDDIR)/deprecated -I$(ZSTDDIR)/legacy \
-	-I$(CONTRIBDIR)/seekable_format -I$(PRGDIR) -DZSTD_MULTITHREAD -DZSTD_LEGACY_SUPPORT=1 $(CPPFLAGS)
+	-I$(CONTRIBDIR)/seekable_format -I$(PRGDIR) -I$(MATCHFINDER_DIR) \
+	-DZSTD_MULTITHREAD -DZSTD_LEGACY_SUPPORT=1 $(CPPFLAGS)
 FUZZ_EXTRA_FLAGS := -Wall -Wextra -Wcast-qual -Wcast-align -Wshadow \
 	-Wstrict-aliasing=1 -Wswitch-enum -Wdeclaration-after-statement \
 	-Wstrict-prototypes -Wundef \
@@ -69,7 +74,8 @@ FUZZ_SRC       := \
 	$(ZSTDCOMMON_SRC) \
 	$(ZSTDCOMP_SRC) \
 	$(ZSTDDICT_SRC) \
-	$(ZSTDLEGACY_SRC)
+	$(ZSTDLEGACY_SRC) \
+	$(MATCHFINDER_SRC)
 FUZZ_SRC := $(sort $(wildcard $(FUZZ_SRC)))
 
 FUZZ_D_OBJ1 := $(subst $(ZSTDDIR)/common/,d_lib_common_,$(FUZZ_SRC))
@@ -78,9 +84,10 @@ FUZZ_D_OBJ3 := $(subst $(ZSTDDIR)/decompress/,d_lib_decompress_,$(FUZZ_D_OBJ2))
 FUZZ_D_OBJ4 := $(subst $(ZSTDDIR)/dictBuilder/,d_lib_dictBuilder_,$(FUZZ_D_OBJ3))
 FUZZ_D_OBJ5 := $(subst $(ZSTDDIR)/legacy/,d_lib_legacy_,$(FUZZ_D_OBJ4))
 FUZZ_D_OBJ6 := $(subst $(PRGDIR)/,d_prg_,$(FUZZ_D_OBJ5))
-FUZZ_D_OBJ7 := $(subst $\./,d_fuzz_,$(FUZZ_D_OBJ6))
-FUZZ_D_OBJ8 := $(FUZZ_D_OBJ7:.c=.o)
-FUZZ_DECOMPRESS_OBJ := $(FUZZ_D_OBJ8:.S=.o)
+FUZZ_D_OBJ7 := $(subst $(MATCHFINDER_DIR)/,d_matchfinder_,$(FUZZ_D_OBJ6))
+FUZZ_D_OBJ8 := $(subst $\./,d_fuzz_,$(FUZZ_D_OBJ7))
+FUZZ_D_OBJ9 := $(FUZZ_D_OBJ8:.c=.o)
+FUZZ_DECOMPRESS_OBJ := $(FUZZ_D_OBJ9:.S=.o)
 
 FUZZ_RT_OBJ1 := $(subst $(ZSTDDIR)/common/,rt_lib_common_,$(FUZZ_SRC))
 FUZZ_RT_OBJ2 := $(subst $(ZSTDDIR)/compress/,rt_lib_compress_,$(FUZZ_RT_OBJ1))
@@ -88,9 +95,10 @@ FUZZ_RT_OBJ3 := $(subst $(ZSTDDIR)/decompress/,rt_lib_decompress_,$(FUZZ_RT_OBJ2
 FUZZ_RT_OBJ4 := $(subst $(ZSTDDIR)/dictBuilder/,rt_lib_dictBuilder_,$(FUZZ_RT_OBJ3))
 FUZZ_RT_OBJ5 := $(subst $(ZSTDDIR)/legacy/,rt_lib_legacy_,$(FUZZ_RT_OBJ4))
 FUZZ_RT_OBJ6 := $(subst $(PRGDIR)/,rt_prg_,$(FUZZ_RT_OBJ5))
-FUZZ_RT_OBJ7 := $(subst $\./,rt_fuzz_,$(FUZZ_RT_OBJ6))
-FUZZ_RT_OBJ8 := $(FUZZ_RT_OBJ7:.c=.o)
-FUZZ_ROUND_TRIP_OBJ := $(FUZZ_RT_OBJ8:.S=.o)
+FUZZ_RT_OBJ7 := $(subst $(MATCHFINDER_DIR)/,rt_matchfinder_,$(FUZZ_RT_OBJ6))
+FUZZ_RT_OBJ8 := $(subst $\./,rt_fuzz_,$(FUZZ_RT_OBJ7))
+FUZZ_RT_OBJ9 := $(FUZZ_RT_OBJ8:.c=.o)
+FUZZ_ROUND_TRIP_OBJ := $(FUZZ_RT_OBJ9:.S=.o)
 
 .PHONY: default all clean cleanall
 
@@ -143,6 +151,9 @@ rt_prg_%.o: $(PRGDIR)/%.c
 rt_fuzz_%.o: %.c
 	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
 
+rt_matchfinder_%.o: $(MATCHFINDER_DIR)/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $(FUZZ_ROUND_TRIP_FLAGS) $< -c -o $@
+
 d_lib_common_%.o: $(ZSTDDIR)/common/%.c
 	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
 
@@ -167,6 +178,9 @@ d_prg_%.o: $(PRGDIR)/%.c
 d_fuzz_%.o: %.c
 	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
 
+d_matchfinder_%.o: $(MATCHFINDER_DIR)/%.c
+	$(CC) $(FUZZ_CPPFLAGS) $(FUZZ_CFLAGS) $< -c -o $@
+
 simple_round_trip: $(FUZZ_HEADERS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_simple_round_trip.o
 	$(CXX) $(FUZZ_TARGET_FLAGS) $(FUZZ_ROUND_TRIP_OBJ) rt_fuzz_simple_round_trip.o $(LIB_FUZZING_ENGINE) -o $@
 
diff --git a/tests/fuzz/zstd_helpers.c b/tests/fuzz/zstd_helpers.c
index 2797ed726..c9fcdd5bf 100644
--- a/tests/fuzz/zstd_helpers.c
+++ b/tests/fuzz/zstd_helpers.c
@@ -17,6 +17,7 @@
 #include "fuzz_helpers.h"
 #include "zstd.h"
 #include "zdict.h"
+#include "matchfinder.h"
 
 const int kMinClevel = -3;
 const int kMaxClevel = 19;
@@ -70,6 +71,17 @@ ZSTD_parameters FUZZ_randomParams(size_t srcSize, FUZZ_dataProducer_t *producer)
     return params;
 }
 
+static void setExternalMatchFinderParams(ZSTD_CCtx *cctx, FUZZ_dataProducer_t *producer) {
+    ZSTD_registerExternalMatchFinder(
+        cctx,
+        NULL,
+        simpleExternalMatchFinder
+    );
+    setRand(cctx, ZSTD_c_enableMatchFinderFallback, 0, 1, producer);
+    FUZZ_ZASSERT(ZSTD_CCtx_setParameter(cctx, ZSTD_c_nbWorkers, 0));
+    FUZZ_ZASSERT(ZSTD_CCtx_setParameter(cctx, ZSTD_c_enableLongDistanceMatching, ZSTD_ps_disable));
+}
+
 void FUZZ_setRandomParameters(ZSTD_CCtx *cctx, size_t srcSize, FUZZ_dataProducer_t *producer)
 {
     ZSTD_compressionParameters cParams = FUZZ_randomCParams(srcSize, producer);
@@ -122,6 +134,12 @@ void FUZZ_setRandomParameters(ZSTD_CCtx *cctx, size_t srcSize, FUZZ_dataProducer
     if (FUZZ_dataProducer_uint32Range(producer, 0, 1) == 0) {
       setRand(cctx, ZSTD_c_targetCBlockSize, ZSTD_TARGETCBLOCKSIZE_MIN, ZSTD_TARGETCBLOCKSIZE_MAX, producer);
     }
+
+    if (FUZZ_dataProducer_uint32Range(producer, 0, 10) == 0) {
+        setExternalMatchFinderParams(cctx, producer);
+    } else {
+        ZSTD_registerExternalMatchFinder(cctx, NULL, NULL);
+    }
 }
 
 FUZZ_dict_t FUZZ_train(void const* src, size_t srcSize, FUZZ_dataProducer_t *producer)